Construction company York Civil has been awarded the contract to design and build the projects at a cost of $32.1 million and will create about 50 to 60 new jobs. The works will begin in April, with completion expected in early 2017.

The bridge and busway will be built from the current James Street bus bridge over the Graham Farmer Freeway to Charles Street. Bus lanes will be built along Charles Street to Violet Street.

"This will result in the removal of more than 1,000 buses a day from James and Fitzgerald streets in Northbridge, alleviating traffic congestion and improving local amenity and access," Mr Nalder said.

"This is a great congestion buster for our city, with benefits for bus users and motorists.

"Northern suburbs passengers commuting to the CBD could have their journey times reduced by up to six minutes during peak times.

"About 16,000 passengers a day will travel over the bridge and busway."

The Minister said the bus bridge and busway would be vital for bus reliability and to cope with growing future demands on public transport.

Key features of the project include James Street exit from Mitchell Freeway relocating to Roe Street to ease the burden on the James and Fitzgerald streets intersection, and the Cleaver and Newcastle streets intersections being modified to allow buses access to Cleaver Street.

Fact File

A bus takes up the road space of about 2.5 cars but can carry 60 to 100 passengers depending on its size. An average car carries 1.2 passengers. By giving priority to buses in some instances, more people can be moved faster on a road with shared traffic

Main Roads WA is delivering the project on behalf of the Public Transport Authority

The bus bridge and busway will allow for the new busport to operate efficiently and at the required capacity